The invention relates to a method for decreasing the alcohol content of alcohol-containing beverages, particularly wine and sparkling wine, as in accordance with the reverse osmosis method while at least aromatic substances are re-fed to the dealcoholized beverage.
A separating method of this sort, particularly in connection with alcohol extraction by hyper filtration, also termed reverse osmosis, from beer constituents the prior art (DDS RO system for alcohol extraction by the DDS RO Division A/S DE DANSKE SUKKERFABRIKKER, Nakskov, Denmark). It is one of the advantages of this method that there is no thermal deterioration of the beer, because hyperfiltration can be conducted within a wide temperature range. During hyperfiltration, the beer is maintained under CO.sub.2 pressure so that degassing or oxidation is avoided. The energy consumption finally, for this process is relatively low because the pump pressure is the only driving force.
In the application of reverse osmosis to wine, aroma losses were in the first instance experienced which however may be reduced by suitable membranes. Aromatic substances of the wine may be re-fed to the dealcoholized wine. A disadvantage however is the high water consumption for washing out the alcohol from the wine, which constitutes a multiple of the amount of wine (Die Weinwirtschaft, No. 1/13 Jan. '84, p. 25 "Wein ohne Alkohol" ("Wine without alcohol")).
With a view to the required high addition of foreign water for performing the above-mentioned reverse osmosis process, the latter is not economical. Moreover, when the foreign water is added in the form of tap water, this foreign water may lead to undesired, or non-permitted, effects on the beverage to be dealcoholized, particularly when the alcohol content of sparkling wine is to be reduced.
When decreasing the alcohol content of wine or sparkling wine, care should further be taken that not only the aroma substances should be retained but also the extraction substances which, together with the aromatic substances, form so-called component substances. In case of the reverse osmosis process, too, extract substances are removed from wine or sparkling wine to be dealcoholized, and this the more so the more alcohol is removed.
Because of the removal of the component substances, the wine or the sparkling wine cannot be dealcoholized by pressurelessly conducted dialysis as is possible in the alcohol reduction of beer. For the alcohol reduction of beer, hollow fibres of "Cuprophan" (registered Trademark) are particularly employed, which constitute a natural product from cotton linters. Alcohol reduction is obtained by the alcohol concentration gradient.
This application of the dialysis as a separation method which is possible for beer cannot simply be applied to wine or sparkling wine because the component substances of these beverages migrate through the relatively great pores of the hollow fibres and are removed together with the alcohol.
In accordance with the (German) Regulations concerning wine, liqueur wine and wine-containing beverages, the production of "sparkling beverages" is also provided on the basis of wine together with fermentation carbon dioxide or by adding carbon dioxide if the reduction of the alcohol is conducted under careful dealcoholization in the vacuum process, i.e. by vacuum distillation. In these beverages however produced from such direct distillation, a major part of the aromatic substances in the wine are missing, and in case of higher temperatures it is even possible that heat damages, such as a so-called boiling tone may appear (Die Weinwirtschaft, loc. cit.).